In coating materials, pigments, which are solid materials, are most often stably dispersed in a solvent by using surfactants or the so-called pigment dispersants such as polymer compounds having a polar group. However, with coating films using black coating materials or dark-color coating films, when the actually coated film is dried, the so-called white blurring can occur, that is, the film can look whitish according to the angle and intensity of light. This phenomenon is particularly clearly observed in aqueous coating materials using water-based emulsion resins.
For example, in the case of black coating materials, a large number of techniques based on the increase in dispersivity of carbon black have been suggested as methods for preventing this phenomenon. PTL 1 to 3 suggest methods for improving the dispersivity of carbon black in coating material resins by using a dispersant. PTL 4 and 5 suggest methods for improving jet blackness by using a carbon black of excellent dispersivity which has been produced by a novel method. In PTL 6 to 10, jet blackness is improved by using a carbon black with stabilized dispersivity which has been produced by a method of polymerizing a vinyl polymer from the carbon black surface. Meanwhile, in coating materials which are also required to have excellent external appearance, as in coating materials for automobiles, better jet blackness and higher distinctness of image are achieved by improving the coating system in addition to increasing the dispersivity of carbon black or organic pigments, as suggested in PTL 11 to 14.
Further, NPL 1 suggests absorbing extra scattered light and obtaining high-saturation coloring by admixing a carbon black to a coating material for preventing light scattering from the coloring pigment surface.